Programming C#, 4th Edition

Chapter 14. Accessing Data with ADO.NET

Many real-world applications need to interact with a database. The .NET Framework provides a rich set of objects to manage database interaction; these classes are collectively referred to as ADO.NET.

ADO.NET looks very similar to ADO, its predecessor. The key differences are that ADO.NET is native to .NET (and isn’t just a wrapper on OLEDB) and that it is primarily a disconnected data architecture. In a disconnected architecture, data is retrieved from a database and cached on your local machine. You manipulate the data on your local computer and connect to the database only when you wish to alter records or acquire new data.

There are significant advantages to disconnecting your data architecture from your database. The biggest advantage is that your application, whether running on the Web or on a local machine, will create a reduced burden on the database server which may help your application to scale well. Database connections are resource-intensive, and it is difficult to have thousands (or hundreds of thousands) of simultaneous continuous connections. A disconnected architecture is resource-frugal.

ADO.NET typically connects to the database to retrieve data, and connects again to update data when you’ve made changes. Most applications spend most of their time simply reading through data and displaying it; ADO.NET provides a disconnected subset of the data for your use, while reading and displaying.

Relational Databases and SQL

Although ...